The invention concerns a process for measuring combustion heat of substances which are fed into a calorimetric bomb and burned in this, whereby the calorimetric bomb is placed, prior to igniting the combustion process, in a water bath situated in an inner tank and this water bath for its part is enclosed by a water jacket situated in an outer container, and whereby a distance is provided between the two bodies of water in the water bath and in the water jacket, and a temperature differential is set, and whereby after, for example, a first measurement, at least one further measurement of the combustion heat of the same and/or of another substance is conducted.
The invention furthermore concerns a device for conducting this process, namely a calorimeter with an internal tank accommodating a calorimetric bomb and with an outer container enclosing this at a distance for accommodating the water jacket as well as with a water feeder to the inner tank and the outer container, and with a water drain at least on the outer container, and furthermore with a heating device arranged in the water feeder which is preferably joined with a controller or a regulating device whereby temperature sensors are arranged in the outer container and the inner tank which are connected with the regulating device for the water feeder.
A process of this type and a device of this type are known from practice. Here, as a rule cold or cool water is at first fed into the outer container through a regulated continuous flow heater whereby the temperature sensor present there ensures that the desired temperature is attained in the water jacket formed by filling the outer container. Here, if the occasion arises, it can be necessary to continue the filling process until the water introduced overflows through a drain, especially in the upper region of this outer container, and the water remaining in this outer container reaches the temperature sought. Then a valve or similar closing means can be shut off by the controller.
After this, filling of the inner tank takes place with the same temperature adjusted on the continuous flow heater.
This method and corresponding calorimeter have proven themselves because the regulating expenditures as well as the expenditures in equipment are relatively low. Nevertheless, however, very exact combustion values can be determined.
Of course, with any measurement, a considerable energy consumption for the continuous flow heater is necessary again and again in order to set the exact temperature for each measurement which also can change again and again with successive measurements since the calorimeter can always contribute a certain warmth itself on the basis of previous measurements.
A process and a device for filling the inner tank of a combustion calorimeter are known from DE 32 20 842 A1, whereby a water storage container with a heating device and a temperature regulation unit for it are provided in order to temper the water for filling the inner tank beforehand. Even here a considerable energy consumption is necessary for heating this storage container.
For this reason, there exists the object of creating a process and a device of the above-mentioned type where energy for the continuous flow heater and if need be also time for setting the exact temperature differential can be saved.
For accomplishing this object, one proceeds such that before the measurement following a previously conducted measurement, the water situated in the inner tank heated above its initial value through the preceding combustion process is at least partially transferred to the outer container, and consequently at least a portion of the combustion heat is used for heating up at least the water jacket in the outer container, and in that then the inner tank is refilled or filled up and the temperature differential is adjusted.
Thus, the combustion heat is used in an advantageous and appropriate manner to temper at least the water jacket so that when filling the water jacket for such a successor measurement, the continuous flow heater is not needed or hardly needed. That means, with such a successor measurement, the energy of the continuous flow heater can be wholly or at least be partially saved for filling the water jacket. If in this connection an excessively high temperature arises in the water jacket, then merely unheated, thus cold water, needs to be added to reach the temperature sought.
For the simplest possible procedure which also requires appropriate time, it is beneficial if preheated water from a continuous flow heater or normally temperature-stabilized water is fed into the inner tank upon filling up for the next measurement following upon a measurement, and if cold and/or not heated water is fed to the outer jacket filled with heated water for adjusting the temperature of the water jacket, and the excess amount of water resulting from this is drained off until the water jacket has reached the sought temperature. The method for adjusting the temperature differential is thus similar to the inherently already known method whereby; however, due to the utilization heat of a preceding measurement, energy is saved. The energy saving can in this manner still be improved in that the inner tank also contains at least a residue of water which was additionally heated by the previous combustion process, whereby a portion of this water is transferred to the outer container, but a remainder can remain in the inner tank and for its part be supplemented and mixed with cold water in order to produce the proper temperature differential.
It is thus especially energy saving if only a portion of the water heated in connection with a measurement is loaded out of the inner tank into the outer container, and a remainder of the water heated by the measurement is left in the inner container, and if the inner tank and the outer container are replenished with cold water, and the water in the inner tank and in the outer container are mixed such that the temperature differential required for a further measurement is formed. In this way, the water to be replenished can be completely untempered so that an energy-consuming preheating of the water required to replenish the outer container and the inner tank can be completely dispensed with.
In this connection, it can be advantageous if so much water heated by a combustion process is moved out of the inner tank into the outer container that the water situated in the outer container has an excessively high temperature for the next measurement, and that the exact temperature differential in relation to the inner tank is adjusted by replenishing by cold or not tempered water. Due to the previous combustion process, the inner tank contains heated water such that with this in the outer jacket, an at first excessively high temperature can be adjusted so that setting the exact temperature to a certain extent can be downwardly adjusted from an excessively high initial value which can be accomplished in a very simple manner by mixing in cold water-if need be in connection with simultaneous mixing or stirring of this water, whereby advantageously with this type of temperature adjustment, no more outside energy is needed.
The temperature in the inner tank and in the outer container can be measured when transferring heated water into the outer container and when replenishing with cold water, and introducing the water to be replenished can be regulated through valves or the like. In this way, the introduction of the amount of cold water can be adapted to the requirements in question without having to allow for a great loss of time.
An especially advantageous refinement of the process of the invention can include that during filling and setting the temperature in the inner tank, the temperature of the water is recorded and determined by a computer in anticipation, and in that the tempering of the water in the outer container takes place before the end of the temperature balancing in the inner tank between the added water, the calorimetric bomb and the inner partition.
Through this method and the advance calculation of the mix temperature, time can be saved in connection with the preparation and implementation of the measuring process. At the same time, the temperature of the calorimetric bomb and the entire calorimeter can be taken into consideration in this connection which accordingly has an effect upon the mixture temperature of the water.
The device mentioned at the beginning serving to conduct the process for accomplishing the object can be characterized in that the water feed to the outer container and to the inner tank is at all times arranged in the lower region, and in that a drainage or overflow is arranged in the region of the upper edge of the outer container, and the feed to the inner tank is alternatively usable as a drain. Consequently, a single water feed results which is usable through the appropriate valves for feeding the outer container and the inner tank, and is also usable for transferring water out of the inner tank into the outer container.
At the same time, it is beneficial if a single water feed is provided with a branching, and in any given case, a feeder leads from the branching to the outer container and an additional feeder leads to the inner tank, and the branch for supplying the inner tank usable as a drain is closably connected through a valve with the branching and the feeder branch to the outer container. This results in a conduit guide which can be manufactured relatively simply and in a space-saving manner and is also relatively operable through control devices in order to fill the outer container and the inner tank in the sequence necessary to implement the process, or to transfer water out of the one container into the other and then once again to be able to be able to mix with fresh water.
Here, a continuous flow heater is arranged in the feed in front of the branch for tempering the water introduced for the necessary tempering of the water in connection with an initial tempering, so that the inner tank as well as the outer jacket can be filled with appropriately heated water if combustion heat is not yet available from a preceding measuring process or, however, in the course of a measuring series, a retempering of the feed water nevertheless becomes necessary owing to a somewhat long interruption.
The water feed for the water can advantageously and simply be connected or connectable with a typical stationarily installed water conduit. Consequently, the device can be installed everywhere in a simple manner wherever it is needed or is appropriate insofar as a water conduit is available or will possibly correspondingly be laid.
For an exact measurement, it is appropriate if the partition at least of the outer container is heat insulated.
An appropriate configuration of the device can be provided in that in the inner tank, especially for regulating or adjusting the water temperature, an agitator is arranged for rotating the water situated in the inner tank and, preferably in an outlet conduit, a pump is arranged. While the agitator ensures a rapid intermixing of the water in the inner tank and intermixture, takes place in the outer container through the inflow technique, the pump in the outlet conduit of the outer container can accelerate the process of pumping the excess water out of the outer container if this must be overfilled when setting an exact temperature and temperature differential.
In the outflow conduit of the water which can be sucked or discharged out of the outer container, a valve which is closed during measurement can be arranged behind the pump. If in contrast water should be let out, this valve can also be opened.
For the exactitude of filling with the necessary amount of water, especially of the inner tank, it is appropriate if a cover is arranged on the upper side of the inner tank which, on its underside facing the interior of the inner tank, bounds a space conically tapering especially upwardly, on the highest point of which a filling level sensor is arranged, and if this cover is sealed off in relation to the inner tank through a capillary slot. In this way, a precise filling can thus take place in the interior of the inner tank where already the slightest level deviations of the tapering space of the cover can be recognized by the filling level sensor, and if need be can correspondingly be compensated for. The capillary slot brings about a good sealing, nonetheless makes possible, however, an overflow of the water in the event that this is expanded owing to heating. It can thus be ensured that the inner tank is sealed off by the cover such that no fluid can exit, but that the position of the cover and the inner volume always agree for repeatable fillings.
At the same time, an additional annular slot or similar space can be arranged above the capillary slot for accommodation of the water exiting owing to expansion during heating. Consequently, the overall amount of water itself then remains preserved if the water of the inner tank expands due to heating. With the aid of the filling level sensor situated on this cover, the water feeder or a filling level valve situated in this can be closed off in any case if the free residual volume not filled up by water in the tapering space of the cover is negligibly small. Slight fluctuations in height of the water level at this place consequently have practically no noticeable effect on the overall volume, and consequently also not on the measurement.
Chiefly in the combination of single or several of the previously described features and measures, there thus results a calorimeter with a vessel for sampling and combusting the sample under increased oxygen pressure, an inner tank for accommodating this vessel and for accommodating a certain amount of water as well as a temperature sensor for measuring the temperature in this inner vessel with an external outer container which is filled with tempered water and in which the inner tank is mounted through an air gap or distance as insulation and through fixation by bracings, and is surrounded by this, and serves for energetic decoupling from the environment. Here, the water from the water conduit or if need be also out of another external water feeder can be heated for tempering by a heat exchanger by opening the shutoff valve as long as such water flows toward the discharge through the outer tank though the pump and/or a valve until the necessary temperature is reached. After this temperature is reached, the inner tank is filled up by opening a valve inside the water feeder and by closing the valve at the outlet of the outer container, and after reaching the filling level sensor arranged in particular within the tapering space of a cover, this valve is closed again, whereby readiness for measuring is attained. With a subsequent measurement and additional consequent measurements, the heated water situated within the device and in particular also the combustion heat arising, which further heats up at least the water in the inner tank, can be used in order to set the proper initial temperature and initial differentials without, nonetheless, the necessity of heating up added water.
Advantageously, the warm up times are dispensed with which would otherwise accrue if the calorimeter is shut off during a pause. During the measurement in and the pauses, no water needs to be tempered or rotated which means a lower energy consumption, at least during measurement.